Accepted Answer

A script bug exists w/Leliana if you raised her approval too high before triggering conversation and was fixed as of patch 1.02. If you have not updated your game, do so!

Also be sure to enter and exit the camp a few times to trigger other parts of the conversation, if I remember correctly the part where she comes clean about her lie happens automatically upon entering the camp rather than when starting to talk to her.

If you triggered the conversation correctly, you must then have her in your active party while traveling to start a random event which directs you to Marjolaine in Denerim. <--- many people miss this part.